Peel 3 very ripe bananas (the blacker the better) and mash them in a large bowl with a fork until almost smooth. A few lumps are fine.
Add 80ml melted butter, 150g sugar, 1 beaten egg, and 1 tsp vanilla to the mashed bananas. Stir until well combined.
Sprinkle over 1 tsp baking soda and a pinch of salt. Add 190g plain flour and fold gently until just combined — lumpy batter is perfect.
Pour batter into a greased 22×12cm loaf tin. Bake at 175°C (350°F) for 55–65 minutes until a skewer inserted in the centre comes out clean. If the top browns too quickly, tent with foil after 40 minutes.